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Autoxidation of beech condensate
2003 - IRG/WP 03-40261
Liquid effluent from steaming beech wood was studied. The effluent contains many phenolic compounds which can present a significant toxicity. The effluent was treated by oxidation was carried out at 250 rpm for 30 min with NaOH. This was followed flocculation with CaCl2 for 30 min. The influence of parameters such as pH, time of autoxidation were studied. Experimental results reveal the electrostatic interaction between the oppositely charged wood extracts after oxidation and flocculation. The increase in aqueous phase pH resulted in enhanced removal of wood extracts from water. The effect of pH is explained based on oxygen uptake.
M Irmouli, J P Haluk


Kiln drying of CCA-treated wood - Some safety and environmental considerations
1987 - IRG/WP 3443
Vapours and condensate from a condenser kiln in which CCA-treated wood was being dried have been collected and analysed. The concentrations of arsenic, copper and chromium found in the vapours from the drying process were well below Swedish threshold limit values. The contents of arsenic and chromium were also low in the condensate, although the copper content was fairly high. The latter result was probably because the low pH of the condensate caused some copper to be leached out from the copper pipes of the dehumidifier device. If precautionary measures are taken when condenser type kilns are constructed in order to prevent the leaching of heavy metals by low pH condensate liquors, there would seem to be no safety or environmental problems with this type of kiln.
J Jermer, B Lundberg


Chemical Remediation of Beech Condensates
2004 - IRG/WP 04-50221
In the present work, The beech wood condensate are subsequently separated from the aqueous phase. Experimental results reveal the electrostatic interaction between the oppositely charged wood extracts after oxidation and Ca(OH)2. The influence of parameters such as pH, oxidation were studied. The increase in aqueous phase pH resulted in enhanced removal of wood extracts from water. The effect of pH is explained based on oxygen uptake. The organic compounds found in this type aqueous effluent are also responsible for brown color. The effectiveness of the treatment process in the abatement of such toxicity was monitored by following the total phenols concentration decay, COD and color reduction.
M Irmouli, J P Haluk


Less pollution due to technical approaches on accelerated steam fixation of chromated wood preservatives
1988 - IRG/WP 3487
Steaming of freshly treated wood at 100°C to 120°C initiates a spontaneous fixation of copper-chromate-containing wood preservatives. For the performance, a suitable anticorrosive equipment is necessary. Good results can be achieved using a separate steaming equipment which allows a rapid heating of the wood. While warming-up, in the wood some preservative solution extends and can be partly extruded. In addition, minor condensation takes place on the surface of the wood and on the walls of the steaming device. Depending on the velocity of the steam supply, it may contain droplets of the wood preservative used. The heated timber itself evaporates water with no detectable ingredients of the preservative. Altogether steam fixation is a promising method to reduce pollution by wood recently treated with water-borne preservatives and allows its use soon after treatment.
H Willeitner, R-D Peek


Fixation of chromated wood preservatives through technical drying
1990 - IRG/WP 3623
Twin samples of sawn timber of Pinus sylvestris and Picea sp. were treated with copper-chromate-containing wood preservatives and subsequently kiln resp. air dried. After drying, the distribution of preservative and rate of fixation were determined. Drying of freshly treated wood in a condenser type kiln at temperatures of 60°C and 80°C and in a vacuum type kiln at 55°C with a pressure of about 200 hPa leads to an almost complete fixation of copper-chromate-containing wood preservatives after about 70 to 100 hours resp. 10 hours depending on the drying schedule applied. In the course of drying the amount of preservative increases on the wood surface. Chromium from treated wood was not found in the "condensate" of the condenser type kiln. Further experiments are ongoing with the vacuum type kiln for collection and analyses of "condensate".
R-D Peek, H Klipp